Writing tests for AR validations

order.rb

class Order < ActiveRecord::Base

  ...
  
  validates :customer_id, 
            :company_id, 
            :credit_card_id, 
            :tip,
            :delivery_location, 
            presence: true

  ...
end

order_test.rb

class OrderTest < ActiveSupport::TestCase

  ...

  [ :customer_id, :credit_card_id, :delivery_location, :company_id, :tip ].each do |field|
    should validate_presence_of field
  end

  ...

end

The only thing this set of tests does is make sure that the validations don't get removed for the set of fields specified. These tests DO NOT make sure that the validations work - that's ActiveRecord's job. I've specified a correct validation, and I want to make sure that it stays in that class definition. I must trust ActiveRecord to take my correct validation and do the right thing, which is to return the correct value from the .valid? method.

IMHO if this is some sort of double check (like "am I really sure I should remove those validations because I would have to go modify the tests too") it's not something I would want to write.

I used to write lots of tests on AR, on the router, etc. None of these are actually worth the effort. What's worth the effort though is to isolate the app from the framework, and test the interactions. YMMV :-)